1. Field of the Invention
This invention relates to a detector for detecting the presence of a particular gas in a mixture of gases and in particular to a gas detector which utilizes diffusion through a piece of material which exhibits differential permeability.
2. Prior Art
Our earlier British patent specification No. 1452574 published on the 13th Oct., 1976 describes a simple gas detector for detecting sudden and abrupt changes in the concentration of a particular gas in a mixture of gases. The detector is intended to be used to initiate the collection of carbon dioxide evolved from a fermentation process when the concentration of carbon dioxide in the mixture of gases evolved from the fermentation process exceeds a predetermined value. This detector is robust and reliable in use but it can only be used in situations where there is a sudden and large change in the concentration of the particular gas to be detected.